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  • Nov 3, 2025

When fertility treatments and breastfeeding collide

If you’re reading this, you might be:

  • Already breastfeeding and considering another pregnancy (with or without fertility treatment)

  • Wanting to continue to breastfeed while pursuing fertility treatment

  • Worried about what fertility treatment might mean for your milk supply or for your baby/toddler who is nursing

Here’s what Emma Pickett lays out: she hosted a podcast episode called “Lactation and Fertility” in which she talks with Carol Smyth about exactly this intersection.

  • Breastfeeding isn’t a guaranteed barrier to fertility, but it can influence it.

  • Fertility treatments may pose special considerations when a person is already breastfeeding.

  • The evidence is thin — we’re navigating “what we know”, “what we suspect”, and “what we don’t know (yet)”.

What the evidence says: breastfeeding can affect fertility

  • Lactation’s effect on the menstrual/ovulation cycle

  • The act of suckling suppresses the hypothalamus-pituitary-ovary axis (i.e., GnRH pulsatility is suppressed) which reduces the release of LH & FSH, delaying follicle development.

  • This means that even when periods return, ovulation may be sub-optimal. Follicle development may be incomplete, leading to a shorter luteal phase (which can reduce chances of successful implantation and maintenance of pregnancy).

  • The “lactational amenorrhoea method” works because of these physiological suppressions — i.e., heavy frequent suckling does suppress fertility temporarily. But once feedings reduce, the suppression lifts.

2. What this means for trying to conceive while breastfeeding

  • You can get pregnant while breastfeeding. It happens. But if you’re hoping to conceive soon while still nursing/tandem feeding, you may hit slower response or “sub-fertile” states.

  • Emma and Carol emphasise that the amount/frequency of suckling, the stage of feeding (exclusive vs. partial vs. toddler nursing), nutrition, parental age, stress, and prior fertility history all greatly modify outcomes.

  • They stress that the worst-case scenario is: continuing heavy frequent suckling might delay return of optimal fertility.

  • As Carol states: “When a woman’s menstrual cycle returns post-partum in the presence of continuing to breast-feed, it is possible that she may … not have a mature egg that is capable of being fertilised.”

3. What about fertility treatments while breastfeeding?

  • Many fertility treatment protocols (especially IVF) assume control of the hormonal environment. Lactation introduces variability (through suckling stimulus and prolactin/pituitary feedback). Emma references this in her blog: “Many clinics will ‘require’ women to stop breastfeeding.”

  • Some medications used in fertility treatment are not compatible with breastfeeding (or have unknown safety profiles). For example: the Letrozole (aromatase inhibitor) is listed as not compatible with breastfeeding in a UK fact sheet.

  • On the other hand, some agents (e.g., synthetic human chorionic gonadotropin, hCG) may be compatible.

  • The takeaway: when fertility treatment is on the table, decision-making about continuing breastfeeding or making adjustments becomes highly individual, and should involve the fertility specialist, lactation consultant, and you (the parent) as informed decision-maker.

4. What we don’t fully know — and what to watch out for

  • How exactly much nursing (frequency/pattern) results in significant suppression of fertility? The threshold is individual.

  • The exact risk (if any) of continuing to breastfeed into fertility treatment cycles, on outcomes like ovulation quality, implantation, miscarriage, and live birth.

  • How much weaning (or reduction in nursing) might help in preparing for fertility treatment, vs. how much you want/need to continue the nursing relationship.

  • Long-term outcomes for milk supply, for the older nursling, if a parent tries to conceive while still breastfeeding (especially if using treatments).

  • How to counsel for “tandem nursing & new pregnancy & subsequent fertility treatment” with an evidence base strong enough to give definite guidance.

Emma Pickett acknowledges all of this: the message is not fear, but informed choice. We must hold space for complexities and for the emotional load of both fertility and feeding.

Practical guidance for parents

1. Clarify your goals & priorities

  • Ask yourself: What is more important right now – continuing the breastfeeding relationship, or optimizing chances of conception (with or without treatment)?

  • There’s no “one right answer”. Your feeding relationship is valid; so is your desire for another baby. The goal is balancing your values & biology & medical context.

  • If you’re using assisted fertility, ask your clinic whether they require weaning, or whether they can work with you whilst you continue feeding.

2. Track and understand your body

  • Consider tracking your cycle, ovulation, luteal phase length, etc., especially if you are trying to conceive. Carol Smyth’s blog suggests a short luteal phase may signal less than ideal fertility while breastfeeding.

  • Monitor how your feeding pattern looks: frequent night nursing? More than 4-5 feeds across 24 hours? Heavy stimulation might correlate with greater suppression.

3. Adjust feeding only if it aligns with your goals

  • If your priority is conceive-soon and fertility treatment is imminent, you may choose to gently reduce nursing frequency (especially night feeds or very short sessions) to reduce suckling stimulus — and talk with a lactation consultant about how to do that without abrupt weaning (to protect milk supply and the older nursling’s emotional well-being).

  • If your priority is continue breastfeeding, accept that conception may take longer, and work with your provider on cycle optimization (charting, nutrition, stress reduction, maybe supplements where appropriate) while continuing to feed.

  • Make the decision that YOU choose, not one driven purely by “you must wean to conceive” messaging.

4. Work as a team: fertility specialist & lactation consultant

  • Bring your lactation consultant into the fertility conversation: medications, cycles, supply, older nursling.

  • Ask your fertility team: “Does this protocol require me to stop nursing or reduce feeds? What’s their evidence basis? Are there alternate protocols for parents still feeding?”

  • And vice-versa: Ask your lactation consultant: “If I start fertility treatment, how might that affect my supply? How can I protect supply while managing the fertility path?”

5. Protect your milk supply (if continuing nursing)

  • Ensure you’re well-nourished, hydrated, getting rest (ha!) — because if you’re aiming to conceive and feed, your body is doing double duty.

  • Watch for signs of supply dip: increased fussiness of the nursling, more frequent feeds, baby switching sides, drop in expressed volumes. Especially if younger baby (<12 months).

  • Consider expressing selectively if you anticipate periods of lower production (e.g., during treatment/medication cycles), to relieve pressure or maintain milk volume.

6. Manage the emotional terrain

  • Fertility journeys + breastfeeding journeys both come with emotional highs & lows. Feeding while trying to conceive (or through fertility treatment) can amplify tension: guilt, anxiety, “am I harming supply?”, “am I delaying my next baby?”, “what about my toddler?”

  • Have emotional support: peer group, counsellor, partner/family. Emma’s and Carol’s work reminds us: you are not alone and you deserve compassionate support.

  • Remember: whether you continue nursing or shift to another pattern, your choices are valid. The feeding relationship doesn’t define your worth, nor does fertility speed or number of children.

Summary: your map for this intersection

  • Breastfeeding has a real physiological effect on fertility (through hormonal suppression) — that’s the biology.

  • Fertility treatments add another layer of complexity (medications, cycles, specialist protocols) and nursing may influence how smooth that path is.

  • Evidence about how fertility treatment and continued nursing interact is limited, so decisions are based on best practice, individual context, not guaranteed rules.

  • The feminist-forward approach: support your autonomy. Don’t let a clinic tell you “you must wean” without exploring why and how it fits you.

  • In practice: set your priorities, gather your team, make a plan (which may evolve), protect your milk supply if you wish to continue nursing, track your fertility markers, and regulate your emotional wellbeing.

Final note

Think of your body as a wise old tree — deeply rooted in the present nursing relationship, yet reaching branches toward new growth (whether that’s another baby, fertility treatment, or sim

ply the passage of your feeding journey). The sap of lactation flows, and in that flow, your fertility pathway adapts. There’s no shame in adjusting the flow, no guilt in shifting direction, no binary of “nurse forever/stop to conceive”. There is only your rhythm — your choice — and the courage to honour both what you feed now and what you hope to grow next.

Sources and further reading

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